I highly doubt that Jane is Austen's mouthpiece. Jane's defining characteristic is her almost preternatural goodness in contrast to the highly amusing flaws of

I highly doubt that Jane is Austen's mouthpiece. Jane's defining characteristic is her almost preternatural goodness in contrast to the highly amusing flaws of the rest of the cast. I think it's unlikely Austen would use such a "perfect" character as her own stand-in. Jane's marriage is also by far the least impulsive of the four marriages depicted in the novel. It is the culmination of the longest arc, and the fulfillment of the longest-held hopes.